Fuel-Powered rock breaker

Abstract

The invention relates to a fuel-powered breaker machine ( 1 ) which has a cylinder ( 2, 2.3, 2.4 ) with two pistons ( 3, 4 ) disposed therein. The first of the pistons ( 3 ) is adapted to opening and closing at least an inlet aperture ( 5, 6 ) on an inlet side (I) in a cylinder shell wall ( 7 ), and an outlet aperture ( 8 ) on an opposite outlet side (O) in the cylinder shell wall ( 7 ), and, when the apertures ( 5, 6, 8 ) are closed, to compressing against the second piston ( 4 ), which acts as the working piston of the breaker machine ( 1 ), an ignitable air/fuel mixture which is admitted via the inlet aperture/apertures ( 5, 6 ). The first piston ( 3 ) has a crown ( 11 ) which is shaped correspondingly to a crown ( 10 ) of the second piston ( 4 ) and which on said inlet side (I) has a recess ( 12 ) which serves, when the first piston ( 3 ) is at an upper dead center position, as a combustion chamber into which a spark plug ( 16 ) protrudes via the cylinder shell wall ( 7 ) on the inlet side (I), and, when the first piston ( 3 ) is at a lower dead center position, as an inlet chamber into which the inlet aperture/apertures ( 5, 6 ) leads/lead.

The invention claimed is: 
     
       1. A fuel-powered breaker machine which has a cylinder with a first piston and a second piston disposed therein which are movable within the cylinder along a common geometric axis, the first piston acting as the piston in a crossflow two-stroke engine and is adapted to opening and closing at least an inlet aperture on an inlet side in a cylinder shell wall, and an outlet aperture on an opposite outlet side in the cylinder shell wall, and, when the apertures are closed, to compressing an ignitable air/fuel mixture, which is admitted via the inlet aperture, against the second piston acting as the working piston of the breaker machine and which during operation of the two-stroke engine imparts a reciprocating movement to a push rod connected to the second piston, wherein the first piston has a crown which is shaped correspondingly to a crown of the second piston and which on said inlet side has a recess which serves, when the first piston is at an upper dead center position, as a combustion chamber into which a spark plug protrudes via the cylinder shell wall on the inlet side, and, when the first piston is at a lower dead center position, as an inlet chamber into which the inlet aperture leads, said recess comprises a planar bottom portion and a wall portion which extends transversely from the planar bottom portion towards the crown of the first piston, and said inlet aperture comprises a central inlet aperture arranged on the inlet side for an air/fuel mixture with at least one secondary inlet aperture disposed to a side of said central inlet aperture for a less concentrated air/fuel mixture or fresh air, at least one of said inlet apertures directly connecting a crankcase with the inlet chamber formed from said recess in the first piston when the first piston is in said lower dead center position, the portion of the spark plug protruding into the combustion chamber is located entirely within said recess when the first piston is in said upper dead center position. 
     
     
       2. A breaker machine according to  claim 1 , in which the wall portion is connected to the bottom portion via a rounded transition, is parallel with said geometric axis, and opens out in an arcuate manner towards the inlet side. 
     
     
       3. A breaker machine according to  claim 2 , in which the crown of the first piston is convex and the crown of the second piston is correspondingly concave. 
     
     
       4. A breaker machine according to  claim 2 , in which the secondary inlet apertures lead in where the wall portion meets the cylinder shell wall. 
     
     
       5. A breaker machine according to  claim 1 , in which the secondary inlet apertures lead in where the wall portion meets the cylinder shell wall. 
     
     
       6. A breaker machine according to  claim 5 , in which the crown of the first piston is convex and the crown of the second piston is correspondingly concave. 
     
     
       7. A breaker machine according to  claim 1 , in which the crown of the first piston is convex and the crown of the second piston is correspondingly concave. 
     
     
       8. A fuel-powered breaker machine which has a cylinder with a first piston and a second piston disposed therein which are movable within the cylinder along a common geometric axis, the first piston acting as the piston in a crossflow two-stroke engine and is adapted to opening and closing at least an inlet aperture on an inlet side in a cylinder shell wall, and an outlet aperture on an opposite outlet side in the cylinder shell wall, and, when the apertures are closed, to compressing an ignitable air/fuel mixture, which is admitted via the inlet aperture, against the second piston acting as the working piston of the breaker machine and which during operation of the two-stroke engine imparts a reciprocating movement to a push rod connected to the second piston, wherein the first piston has a crown which is shaped correspondingly to a crown of the second piston and which on said inlet side has a recess which serves, when the first piston is at an upper dead center position, as a combustion chamber into which a spark plug protrudes via the cylinder shell wall on the inlet side, and, when the first piston is at a lower dead center position, as an inlet chamber into which the inlet aperture leads, said recess comprises a planar bottom portion and a wall portion which runs from the bottom planar portion towards the crown of the first piston, and said inlet aperture comprises a central inlet aperture arranged on the inlet side for an air/fuel mixture with at least one secondary inlet aperture disposed to a side of said central inlet aperture for a less concentrated air/fuel mixture or fresh air, the portion of the spark plug protruding into the combustion chamber when the first piston is in said upper dead center position being located entirely within said recess when said first piston is in said upper dead center position. 
     
     
       9. A fuel-powered breaker machine which has a cylinder with a first piston and a second piston disposed therein which are movable within the cylinder along a common geometric axis, the first piston acting as the piston in a crossflow two-stroke engine and is adapted to opening and closing at least an inlet aperture on an inlet side in a cylinder shell wall, and an outlet aperture on an opposite outlet side in the cylinder shell wall, and, when the apertures are closed, to compressing an ignitable air/fuel mixture, which is admitted via the inlet aperture, against the second piston acting as the working piston of the breaker machine and which during operation of the two-stroke engine imparts a reciprocating movement to a push rod connected to the second piston, wherein the first piston has a crown which is shaped correspondingly to a crown of the second piston and which on said inlet side has a recess which serves, when the first piston is at an upper dead center position, as a combustion chamber into which a spark plug protrudes via the cylinder shell wall on the inlet side, and, when the first piston is at a lower dead center position, as an inlet chamber into which the inlet aperture leads, said recess comprises a bottom portion and a wall portion which extends from the bottom portion towards the crown of the first piston, and said inlet aperture comprises a central inlet aperture arranged on the inlet side for an air/fuel mixture with at least one secondary inlet aperture disposed to a side of said central inlet aperture for a less concentrated air/fuel mixture or fresh air, said wall portion of said recess and said at least one secondary inlet aperture arranged so that said wall portion and the flow of said air/fuel mixture or air through said at least one secondary inlet aperture reduces flow of said air/fuel mixture from said central inlet aperture to said outlet aperture when said recess in said first piston serves as said inlet chamber.